Levels of second-hand smoke exposure among non-smoking adults fell by almost 30 per cent after smoke free legislation was introduced in England in 2007.

The most comprehensive study to date of second-hand smoke exposure among non-smoking adults in England, which was funded by the Department of Health, was published on 13 December 2011 in the journal Environmental Health Perspectives.

Researchers analysed data from seven national surveys conducted between 1998 and 2008. These surveys measured cotinine, an indicator of tobacco smoke exposure, in saliva samples from over 30,000 people aged 16 and over.

They showed that levels of exposure to second-hand smoke in non-smokers had been declining in the ten years leading up to smoke free legislation. But even when this decline was taken into account, the introduction of smoke free public places led to significant, additional reductions in exposure. Average exposure fell by 27 per cent immediately following the legislation.

The results further revealed that while there was a marked reduction in the levels of second-hand smoke exposure among those who lived in a smoke free home, those who lived in a home where there was smoking inside showed no significant change in exposure following the implementation of smoke free public places.

Dr Michelle Sims, the first author of the paper, said: “Smoke exposure fell after the introduction of England’s smoke free legislation above and beyond the underlying long-term decline, demonstrating the positive effect of the legislation.

“Nevertheless, some population subgroups appear not to have benefited significantly from the legislation, suggesting that these groups should receive more support to reduce their exposure.

“There is now a large body of evidence documenting the adverse effects of second-hand smoke exposure. In adults it is now known to be linked with coronary heart disease, lung and various other cancers, stroke, chronic respiratory symptoms and adverse pregnancy outcomes.”

Other research has shown that smoke free legislation is also associated with reductions in hospital admissions for heart attacks and asthma in the UK and other countries.

Professor Anna Gilmore, who directed the study, said: “The importance of this study is that it examines the impacts of smoke free policies on adults’ exposure using a specific biological-marker of smoke exposure (rather than self-reported exposure) while simultaneously controlling for underlying declines in exposure.

“To our knowledge it is the first study to do this. The fact it shows marked declines in adult exposure provides further evidence of the important public health benefits of smoke-free policies.”

Smoke-free legislation was implemented in England on the 1st July 2007, making virtually all enclosed public places and workspaces smoke-free. The aim of the legislation was to protect non-smokers and children from the negative consequences of second-hand smoke exposure.

We have found that the second-hand smoke exposure among children has declined markedly in the past 14 years.

Our research, the most comprehensive study to date of second-hand smoke exposure among children in England, was funded by the Department of Health and published on 8 February 2010 in the journal Addiction.

The study, carried out by Dr Anna Gilmore and her team from the University of Bath’s School for Health, reveals that exposure to second-hand smoke among children aged four to 15 has declined steadily since 1996.

We wanted to find out if there were ways to predict the levels of second-hand smoke that children in England are exposed to and whether those levels were changing over time. It was also important for us to understand the levels of childhood second-hand smoke exposure in the years preceding the legislation, to be able to accurately assess the effects of the smoke-free legislation implemented in England in July 2007,

We analysed data from the Health Survey for England conducted between 1996 and 2006 including saliva samples taken from approximately 14,000 children aged between four and 15. The saliva samples were analyzed for a substance called cotinine, an indicator of tobacco smoke exposure.

The results showed that children’s exposure fell by 59 per cent over the 11 year period (from 0.59ng/ml in 1996 to 0.24ng/ml in 2006) indicating that children’s exposure to second-hand smoke has decreased markedly since the mid-nineties. The greatest decline occurred between 2005 and 2006, a period when targeted mass media campaigns on the dangers of second-hand smoke were routinely aired.

The study highlighted that the largest decline was between 2005 and 2006, a time of increased public debate and public information campaigns about second-hand smoke in the lead-up to the 2007 implementation of smoke-free legislation for public spaces.

The research also reveals that second-hand smoke exposure in non-smoking children is highest when one or both parents smoke, when the children are looked after by carers that smoke, and when smoking is allowed in the home. Children from more deprived households were more exposed, and this was still the case even when we took parental smoking status into account.

Declines over this period were greater in children with two smoking parents, with average annual falls of 0.115ng/ml, compared children with a mother who smoked (average annual decline of 0.065ng/ml) and children with non-smoking parents (average annual decline of 0.019ng/ml). As declines were greatest for those children who were most exposed to begin with, the gap in children’s second-hand smoke exposure between children with smoking parents and children with non-smoking parents has lessened.

Dr Michelle Sims, first author of the paper, explained: “The importance of carer and parental smoking and household exposure tells us that reducing exposure in the home is the key to reducing the health risks associated with second-hand smoke exposure in children.”

Dr Anna Gilmore, who led the project, said: “This study shows that the factors which most strongly influence children’s exposure are modifiable. Parents and carers can reduce their children’s exposure to smoke by giving up smoking, or failing this, only smoking outside the house.

“Stopping others from smoking in their house is also important. The fact that children’s exposure has already fallen so markedly shows that making these changes is feasible.”

This research highlights the need for public health interventions aimed at decreasing smoking prevalence and for those who are unable to quit, decreasing smoking in the home.